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tag-icon • tag-icon debian systemd socket-activation
进一步阅读

我有以下单位：

test_socket_activation.socket

[Unit]
Description="************** MY TEST SOCKET ***************"
PartOf=test_socket_activation.service

[Socket]
ListenStream=127.0.0.1:9991

[Install]
WantedBy=sockets.target

test_socket_activation.service

[Unit]
Description="********** MY TEST SERVICE *****************"

[Service]
ExecStart=/home/xxx/sysadmin/systemd_units/socket_based_activation/testservice.sh

[Install]
WantedBy=multi-user.target

测试服务.sh

#!/bin/bash
echo "Socket Service Triggered" > output.txt

理论上，systemd 应该监听 127.0.0.1 端口 9991（通过 test_scocket_activation.socket）。当访问套接字时，systemd 应该调用父单元 (test_scocket_activation.service)，而父单元又应该执行 ExecStart 指令 (testservice.sh) 中列出的脚本，然后创建一个名为 output.txt 的文本文件来通知套接字已被访问。

这按预期工作（即访问套接字时创建了output.txt），除了服务单元（test_scocket_activation.service）随后由于“启动请求重复太快，拒绝启动”而失败，即使套接字仅被访问一次。然后，服务的故障会触发关联套接字的故障，从而停止侦听。

我在这里做了一些测试，这是我的步骤和日志输出：

❯ sudo systemctl start test_socket_activation.socket

❯ sudo systemctl 状态 test_socket_activation.socket

● test_socket_activation.socket - "************** MY TEST SOCKET ***************"
   Loaded: loaded (/etc/systemd/system/test_socket_activation.socket; disabled)
   Active: active (listening) since Thu 2020-03-19 14:08:40 +01; 17s ago
   Listen: 127.0.0.1:9991 (Stream)

Mar 19 14:08:40 toshi systemd[1]: Starting "************** MY TEST SOCKET ***************".
Mar 19 14:08:40 toshi systemd[1]: Listening on "************** MY TEST SOCKET ***************".

❯ 回显“你好” |网猫 127.0.0.1 9991

❯ ls

output.txt  testservice.sh

❯ sudo systemctl status test_socket_activation.service

 ● test_socket_activation.service - "********** MY TEST SERVICE *****************"
       Loaded: loaded (/etc/systemd/system/test_socket_activation.service; disabled)
       Active: failed (Result: start-limit) since Thu 2020-03-19 14:10:42 +01; 9min ago
      Process: 2842 ExecStart=/home/mkr/sysadmin/systemd_units/socket_based_activation/testservice.sh (code=exited, status=0/SUCCESS)
     Main PID: 2842 (code=exited, status=0/SUCCESS)

    Mar 19 14:10:42 toshi systemd[1]: Started "********** MY TEST SERVICE *****************".
    Mar 19 14:10:42 toshi systemd[1]: Starting "********** MY TEST SERVICE *****************"...
    Mar 19 14:10:42 toshi systemd[1]: test_socket_activation.service start request repeated too quickly, refusing to start.
    Mar 19 14:10:42 toshi systemd[1]: Failed to start "********** MY TEST SERVICE *****************".
    Mar 19 14:10:42 toshi systemd[1]: Unit test_socket_activation.service entered failed state.

❯ sudo systemctl 状态 test_socket_activation.socket

● test_socket_activation.socket - "************** MY TEST SOCKET ***************"
   Loaded: loaded (/etc/systemd/system/test_socket_activation.socket; disabled)
   Active: failed (Result: service-failed-permanent) since Thu 2020-03-19 14:10:42 +01; 41s ago
   Listen: 127.0.0.1:9991 (Stream)

Mar 19 14:08:40 toshi systemd[1]: Starting "************** MY TEST SOCKET ***************".
Mar 19 14:08:40 toshi systemd[1]: Listening on "************** MY TEST SOCKET ***************".
Mar 19 14:10:42 toshi systemd[1]: Unit test_socket_activation.socket entered failed state.

❯ sudo Journalctl -u test_socket_activation.service

-- Logs begin at Thu 2020-03-19 14:05:23 +01, end at Thu 2020-03-19 14:17:29 +01. --
Mar 19 14:10:42 toshi systemd[1]: Starting "********** MY TEST SERVICE *****************"...
Mar 19 14:10:42 toshi systemd[1]: Started "********** MY TEST SERVICE *****************".
Mar 19 14:10:42 toshi systemd[1]: Starting "********** MY TEST SERVICE *****************"...
Mar 19 14:10:42 toshi systemd[1]: Started "********** MY TEST SERVICE *****************".
Mar 19 14:10:42 toshi systemd[1]: Starting "********** MY TEST SERVICE *****************"...
Mar 19 14:10:42 toshi systemd[1]: Started "********** MY TEST SERVICE *****************".
Mar 19 14:10:42 toshi systemd[1]: Starting "********** MY TEST SERVICE *****************"...
Mar 19 14:10:42 toshi systemd[1]: Started "********** MY TEST SERVICE *****************".
Mar 19 14:10:42 toshi systemd[1]: Starting "********** MY TEST SERVICE *****************"...
Mar 19 14:10:42 toshi systemd[1]: Started "********** MY TEST SERVICE *****************".
Mar 19 14:10:42 toshi systemd[1]: Starting "********** MY TEST SERVICE *****************"...
Mar 19 14:10:42 toshi systemd[1]: test_socket_activation.service start request repeated too quickly, refusing to start.
Mar 19 14:10:42 toshi systemd[1]: Failed to start "********** MY TEST SERVICE *****************".
Mar 19 14:10:42 toshi systemd[1]: Unit test_socket_activation.service entered failed state.

正如您在上面看到的，套接字仅被访问一次，服务被触发，并且它确实调用脚本来创建output.txt 文件。但不久后，服务因多次尝试启动而失败。

我的问题如下：

  1. 当套接字仅访问一次（通过 echo "hello" | netcat 127.0.0.1 9991）时，为什么服务启动多次？

  2. 当关联的套接字仅被访问一次时，如何避免服务多次启动？

所有答案/意见/见解将不胜感激，谢谢。

答案1

您已经创建了一个Accept=No套接字，其中服务被传递了侦听套接字文件描述符，并且预计将接受连接，并且保持运行。赠品应该是您没有创建模板服务单元，而套接字则需要模板服务单元，Accept=Yes其中服务传递连接的套接字文件描述符。

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